Oct. 23, 1884] 



NA TURE 



619 



From the equivalences 2C = 4H and 3C = 2O 

 it follows that C = 2H 



and O = 3H, 



while from a similar examination of liquids containing chlorine 

 he deduces CI = 7H. 



These equivalences enable him to write down what may be 

 called the hydrogen equivalent, with respect to the value of the 

 number N, of any compound of the four elements in question, 

 i.e. the number of hydrogen atoms, which, if they existed as a 

 molecule in the free state, would constitute a substance for 

 which the value of N at the boiling-point would be the same as 

 for the original substance. Thus, selecting a few substances 

 whose hydrogen equivalents are tolerably evenly distributed 

 over the range that he has examined, he obtains the following 

 table : — 



CH 4 = H 9 

 C„H 6 = H 18 

 CJH 8 = H 17 

 C 3 H 6 2 = H 18 

 C 4 H 8 0, = H 22 



C 8 H 10 = H 26 



C 9 H 12 = H 30 



C 8 H 1S — H 34 



C 8 H 16 2 = H 38 

 Cii)H 2 . 2 = rlj.. 



N 



59-8 

 38-4 

 29 - o 

 27 'o 

 20 - 4 

 16-1 



131 

 10-5 



87 

 77 



From these observations as data, a curve is easily drawn of 

 which the ordinates are proportional to the number of atoms in 

 the hydrogen equivalent and the abscissas to the corresponding 

 value of N ; and it is remarkable that the curve so drawn is of 

 equable curvature, and corresponds equally well, not only to the 

 selected data from which it is plotted, but also to all the other 

 observed values of N, so that by transforming the molecular 

 formula of any liquid into its hydrogen equivalent we can at 

 once find, by reference to the curve, the value of N for the sub- 

 stance, and, by multiplying this by : S-', we obtain the 



1000 

 surface-tension at the boiling-point. 



There are only three liquids for which Prof. Schiff notices 

 that the value of N, as calculated from the curve, differs 

 markedly from the observed value. These are — 

 Amylene(C 5 H, ), for which N(obsd.) = 22, and Ni(calcd.) = 23 - 4 

 Diallyl (C 6 H 10 ) ,, „ =18-4 „ =20-5 



Ethylene-chloride (C 3 H 4 C1 2 ) ,, =24-6 ,, = 20-5 



In the first case the disagreement is explained by the presence of 

 impurity ; in the second, impurity is very possibly the cause ; while 

 in the third it is possible that the equation CI = H 7 is not applicable 

 to substances in whose formula more than a single carbon atom 

 is represented, a point which- the author hopes to clear up by 

 further investigation. We observe, however, that to these dis- 

 agreements should be added the case of ethyl-isobutyrate 

 C 6 H ]2 2 ), for which N as given by the curve is 131, while the 

 observed value was 12*3, a deviation of 7-5 per cent. On this 

 the author makes no remark. 



We will venture here to call attention also to a slight error that 

 pervades all Prof. Schiff's results. We refer to the manner in 

 which he corrects for the meniscus. The importance of this 

 correction is in these measures very considerable, since the total 

 elevation observed is always less than 10 mm. and sometimes 

 less than 5 mm., and the correction is sometimes as much as 2 

 per cent, of the whole. Prof. Schiff, rejecting as insufficiently 

 accurate Laplace's correction, which is based on the assumption 

 that the surface of the meniscus may be regarded as that of a 

 hemisphere of the same radius as the tube, and which consists 

 therefore in adding to the observed height one-third of this 

 radius, prefers to measure the height of the meniscus directly 

 and to take as the correction one-third of the arithmetical mean 

 between the observed height and the radius of the tube. In 

 doing this he assumes that the surface may be regarded as that 

 of a sphere of radius very appreciably greater than that of the 

 tube, and gives a diagram in which it is so represented ; but if 

 this assumption or representation were correct, the laws of capil- 

 lary tubes would be very different from what they are ; more- 

 over, according to theory, the form of the meniscus, and 

 therefore the correction, must always be the same for liquids 

 with the same capillary elevation ; but Prof. Schiff's correction, 

 based on the direct measurement of the meniscus, varies very 

 considerably for elevations that are almost identical, which 



shows that the measures of the meniscus are not to be relied on : 

 thus in the case of ethyl-toluol (para) (C 9 H 2 ) the elevation is 

 •603 cm., and the correction -013 cm., while for isobutyl-formiate 

 (C 5 H 10 O.,) the elevation is -599 cm., but the correction -ooSc.m., 

 and in many cases one of two liquids which must theoretically 

 have the greater correction has in point of fact the smaller. In 

 order to see how far the empirical correction was at fault, we 

 have selected one of Prof. Schiff's measures in which the 

 elevation has about its mean value, and have calculated 

 for comparison the correction of Hagen and Desains, which 

 is based on the very approximately accurate assumption 

 that the meniscus may be regarded as an oblate spheroid, and 

 which is said to have been verified (? in the case of water) for 

 tubes whose diameter attained as much as 4-6 mm. The fol- 

 lowing is the result : — 



Propyl Formiate : observed elevation 6-45 



,, ,, Laplace's correction = - 01046 



,, ,, Hagen and Desains' correction = - 0'I02 



,, ,, SchifFs correction = - °'°7 



Corrected value (Schiff) 6-38 ; (Hagen and Desains), 6-348 mm. 

 It will thus be seen that an error of about \ per cent, 

 in the value of the surface-tension has entered into the result on 

 this occasion, and that more has been lost than gained by sub- 

 stituting the empirical correction for that of Laplace ; in some 

 cases the error will be rather greater. 



The importance in molecular physics of the step which Prof. 

 Schiff lias taken cannot easily be overrated. If it were only 

 that he had found that isomeric substances have the same surface- 

 tension at the boiling-point, that alone would have been a fact 

 of great importance in reference to the interpretation of what 

 we are accustomed to call the internal vapour-tension in a liquid ; 

 but in the system of absolute atomic equivalences with respect to 

 surface-tensi .n, and the knowledge of the manner in which the 

 surface-tension varies with variations of the atomic equivalent, 

 he has given to the physicist now for the first time most important 

 data for correlating the surface-tension with the molecular actions 

 existing expectively in the mass of the liquid and in the vapour 

 above it. A. M. W. 



RESEARCHES ON THE ORIGIN AND LIFE- 

 HISTORIES OF THE LEAST AND LOWEST 

 LIVING THINGS 1 

 ""TO all who have familiarised themselves, even cursorily, with 

 -*■ modern sc entitle knowledge, it is well known that the 

 mind encounters the infinite in the contemplation of minute, as 

 well as in the study of vast natural phenomena. The farthest 

 limit we have reached, with the most gigantic standard of 

 measurement we could well employ, in gauging the greatness of 

 the universe, only leaves us with an overwhelming consciousness 

 of the awful greatness — the abyss of the infinite — that lies be- 

 yond, and which our minds can never measure. The indefinite 

 has a limit somewhere ; but it is not the indefinite, it is the 

 measureless, the infinite, that vast extension forces upon our 

 minds. In like manner, the immeasurable in minuteness is an 

 inevitable mental sequence from the facts and phenomena re- 

 vealed to us by a study of the minute in nature. The practical 

 divisibility of matter disclosed by modern physics may well 

 arrest and astonish us. But biology, the science which in- 

 vestigates the phenomena of all living things, is in this matter 

 no whit behind. The most universally diffused organism in 

 nature, the least in size with which we are definitely acquainted, 

 is so small that fifty millions of them could lie together in the 

 one-hundredth of an inch square. Yet these definite living 

 things have the power of locomotion, of ingestion, of assimila- 

 tion, of excretion, and of enormous multiplication, and the 

 material of which the inconceivably minute living speck is made, 

 is a highly complex chemical compound. We dare not attempt 

 a conception of the minuteness of the ultimate atoms that com- 

 pose tfeu several simple elements that thus mysteriously combine 

 to form the complex substance and properties of this least and 

 lowliest living thing. But if we could even measure these, as a 

 mental necessity, we are urged indefinitely on to a minuteness 

 without conceivable limit, in effect, a minuteness that is beyond 

 all finite measure or conception. So that, as modern physics 

 and optics have enabled us not to conceive merely, but to 

 actually realise, the vastness of spatial extension, side by side 

 ' By Rev. W. H. Dallinger, LL.D., F.R.S., F.L.S., Pres.R M S. 



